In a previous patent by the same inventor titled "NOISE PULSE REJECTION CIRCUIT" issued July 2, 1974 as U.S. Pat. No. 3,822,385, a circuit was disclosed comprising an operational amplifier having a controlled RC network at its inverting input. Such circuit is useful in rejecting pulses having a duration smaller than a predetermined value and as such is utilized as a noise pulse rejector. There are certain applications in which it is required to correct pulses of non-standard duration rather than to reject them. It is for instance often necessary, after noise pulses have been rejected by a circuit similar to that of the above-mentioned patent, to correct the durations of the true pulses and convert them to the standard duration of the respective system.
More specifically in the case of the dial pulse correction, the dial pulses are usually distorted after traversing a transmission medium, such as cable, connecting a transmit and a receive point. The distortion of interest in the present context is a shorting or a lengthening of the original duration of the transmitted pulses. If not corrected, such distortion may result in an error in the telephone number that has been transmitted.